1. Field of the Invention
The invention relates to a method for detecting a rotation angle.
2. Description of the Background Art
A rotary encoder which could be connected to a shaft of an engine is known in the conventional art. The encoder offers the option of determining a rotation angle that is divided into sectors. It could be provided hereby to scan concentrically arranged sector regions of a circle segment of a circular encoder disk simultaneously by a number of sensors. Disadvantages of the rotary encoder are in particular that, on the one hand, a number of sensors are absolutely necessary and, on the other, the arrangement of the encoder disk and associated sensors requires a high structural effort, particularly in regard to adherence to fabrication tolerances, which depends on the required maximum allowable rotation angle measurement error of the encoder system.
It is known from the document “Application-Note, Using the engine position (crank and cam) eTPU functions” by G. Emerson (East Kilbride), Freescale Semiconductor, pages 2 and 3, Section 3, to use a toothed wheel with 35 teeth to detect the rotation angle of the drive shaft of a machine. The toothed wheel has at a predetermined position a tooth gap, whereby the tooth gap could be used as a feature for the start point or end point of a rotation of the toothed wheel and the drive shaft. A sensor could be used for scanning the teeth and the tooth gaps. This technical solution has the following disadvantage in particular: On the one hand, depending on the position of the tooth gap in the worst case, the time between initialization and the provision of information on the rotation angle of the drive shaft is relatively long, namely, when, for example, after the initialization process, for example, during starting of the machine, almost a complete rotation of the shaft is necessary to bring the tooth gap to the sensor.